The splitting of an optical beam into two or more optical beams is an important function in optical communication systems. Optical beam splitters enable a single optical beam from a source such as a laser to be supplied to more than one device. As a result, optical beam splitters are utilized in many devices including splitter arrays, optical interconnects, modulators, and the like.
Typical 1×2 optical splitters consist of an input waveguide, two fan-out arms coupled to the input waveguide at a separation point, and two output waveguides. An input light beam enters the optical splitter and travels through the input waveguide to the separation point. At the separation point, the light beam is split into two light beams by being forced to enter the two fan-out arms. The two light beams then travel through the fan-out arms and out of the optical splitter via the output waveguides.
Since light beams tend to travel in a straight line, and since the fan-out arms typically have a strong curvature at the separation point, a small amount of light from the center of the input light beam will not enter either fan-out arm. This results in a propagation loss in the input light beam and thus a decrease in the intensity of the two light beams exiting the optical splitter.